Method of producing wooden boards secured against warping



Oct. 30, 1951 v A. E. LUNDBERG 2,573,465

METHOD OF PRODUCING WOODEN BOARDS SECURED AGAINST WARPING Filed Dec. 23, 1946 2 SHEETS-SHEET l Oct. 30, 1951 A. E. LUNDBERG 2,573,465

METHOD OF PRODUCING WOODEN BOARDS SECURED AGAINST WARPING Filed Dec. 25, 1946 2 SHEETSSHEET 2 Patented Oct. 30, 1951 METHOD OF PRODUCING WOODEN BOARDS SECURED AGAINST WARPIN G Axel Eugn Lundberg, Sundsvall, Sweden Application December .23, 1946, Serial No. 717,974 In Sweden December 22, 1945 "3 Claims.

(Granted under the provisions of sec. 14, act of March .2, 1927 357 0. G.

The present invention refers to a method of producing wooden parts or workpieces secured against warping. The invention is principally distinguished by the feature that boards, strips or the like are forcibly bent and glued together in their bent condition with the curved surfaces thereof placed on each other, whereupon the block thus obtained is subjected to further treatment to form compound boards, slabs, larger or smaller blocks or the like. The block formed from the elements glued together in their forcibly bent condition is divided in the further treatment, preferably by saw-cuts, the cutting planes of which extend in the longitudinal direction of the curved edges of the glued joints so as to divide the individual surfaces of the glued joints in parts running alongside of each other. The cuts are preferably made so that the cutting planes extend substantially at right angles to the surfaces of the glued joints.

The invention will be described more closely in the following with reference to examples of embodiment of boards or slabs and blocks produced according to the invention and illustrated in the accompanying drawings.

Fig. 1 is a perspective view of blocks consisting of curved boards glued together. Fig. 2 illustrates the disposition of compound boards orslabs .sawn out of the block according .to Fig. V1 in the gluing thereof. Fig. 3 shows a compound board glued together in accordance with Fig. 2. Fig. 4 is an endwise view of the compoundboard according to Fig. 3, and Fig. 5 is also an endwise view of a second example of embodiment relative to the gluing of the strips. Figs. 6 and '7 illustrate further examples of the gluing of blocksand of compound boards cut from a block, respectively. Fig. 8 shows a method of gluing the primary block. Fig. 9 shows a cross section on line X-X in Fig. 8. Fig. 10 and Fig. 11 show embodiments relative to the use of slabs produced in accordance with the method according to the invention.

The block shown in Fig. l is produced by the bending of a numberof strips or boards I, which are glued together in their curved condition. The edge lines 3 of the surfaces 2 of the glued joints will thus extend in arcs along the sides of the block Should one of the individual boards of the block tend toward warping, this would obviously manifest itself so that the board would have a tendency to twist about a longitudinal line of the wood. However, such twisting may be expected to be counteracted by the strip lying adjacent thereto. Slabs or board-like parts are cut out of the block, which parts are likewise secured against warping. These parts mayinturn be glued together, in a manner such that any remaining tendency toward warping will be further counteracted. The block according to Fig. 1 is divided into composite boards or slabs by sawcuts extending in the longitudinal direction of the edges of the glued joints in the manner indicated by the chain-dotted line 4 and the lines .5. 6 and the arrows 1,, respectively. The saw-cuts consequently extend in such manner that. the cutting planes extend substantially at. right: angles to the surfaces 2 of the glued joints.

In Fig. 2, A and B designate two compound boards or slabs cut from the block according to Fig. 1 in the above-stated manner, the end portions of such compound boards (for the sake :of simplicity in the following called boards.) being denoted by a and b and a and b, respectively. If a wider compound board is desired, the board .13 is placed with its longitudinal side 0 against the corresponding longitudinal side c of the board A, so that the board B will take the position shown by chain-dotted lines, in which it is glued together with the board A. When the board B is placed adjacent tothe board A, the first-mentioned board should preferably be turned at the same time in the longitudinal direction, so that the edge a will be brought into the extension of the edge I) of the board A, as indicated by the designations at the chain-dotted slab B in Fig. 2..

Fig. 3 shows a board .glued togethed in the manner described above. This board may in turn be divided into .two boards C and D, Fig. 4, by

means of a longitudinally extendin saw-cut on the chain-dotted, line 8 and in the direction of the arrows 9. The members C and D may then, preferably after at least one of the boards has been turned entirely, be glued together ina-manner such that the sides (2 and al which were previously turned outwardly, will lie in contact.

with each other, the surface of the saw-cut last produced being thus turned outwardly. In this case the boards C and D are thus glued together in the position illustrated by the designations in Fig. 5.

Fig. 6 .shows two boards A and B glued together in the manner set forth with reference to Fig. 2, the glued joint of which boards is denoted by 10. In the illustrated example of embodiment, the curved edges 3 of the glued joints extend in an undulatory fashion, the wave crests touching each other in the glued joint [0. Instead, the boards A and B. may be displaced longitudinally relatively to each other, so that the said. wave crests. will be displaced with respect to one. an.

other (phase displacement). In the manner shown in Fig. 6, two or more blocks from boards or strips glued together may also be glued to each other, particularly if it is desired to saw slabs of a large width from them.

Fig. '7 shows two boards or slabs corresponding to the boards C and D in Figs. 4 and 5. These boards are displaced relatively to each other in such manner that the arcuate or undulatory edges 3 of the glued joints are displaced with respect to each other, before the boards C and D are glued together. The boards A and B of Fig. 2, for example, may be glued together in the same manner.

Figs. 8, 9 illustrate a method of gluing the primary block according to Fig. 1 together. The strips, boards or battens denoted by I are inserted in great lengths of many feet, for instance, into a press, the foundation of which is designated by H, while the movable part thereof is denoted by (2. The latter part presents a lower surface 43 of the undulatory shape which it is desired to impart to the boards. The upper side of the foundation may be constructed in the same manner with an undulatory upper surface, it being preferred, however, to arrange on the foundation a special mould having an undulatory upper surface. The contact surfaces of the boards coated with an adhesive are gued together at a simultaneous bending of the boards, when the movable part I2 is set in a direction against the rigid part II. The gluing of the boards having been completed, the upper portion is cut plane by a saw-cut on the line It. The portion l5 which is thus separated and presents an undulatory upper side, and which should be integral all over its length, is placed in the pressing of the following block beneath the latter, that is to say into the position marked by l5, and is glued to the block then formed. The piece I5 thus serves as a mould in the bending of the boards lying thereabove. The finished block now presents parallel upper and lower sides. The pressing device according to Fig. 8 may be constructed in various ways from a mechanical point of view. The upper part i6 of the press may be rigid, only the part I2 being vertically displaceable. The pressing movement thereof may be eifected with the aid of two or more rubber tubes [1 disposed beside one another and supplied with air or liquid under a high pressure in the pressing operation.

The boards or slabs produced in the manner above described, such as the board A and B or the board C, D, or only one board A, may in turn be bent and glued together, if desired, with similar board in their curved condition. For the production of wood for skis, for example, the boards are then bent in the transverse direction when glued together. A number of boards E thus glued together are shown in Fig. 10, which illustrates a cross section through a ski, the portion of which that forms the running surface is designated by H). The last-mentioned part may also be produced from plane elements glued together in accordance with the invention.

Fig. 11 shows a cross section of a beam may also be produced with the aid of the woodenv material glued together. If desired, a single board or slab (or block) F may be made use of,

said slab having a securing bar glued thereto at.

the one or both of the longitudinal edges thereof,

glued together from boards F produced out of blocksv said securing bar corresponding to the horizontal shanks of the I-beam.

When slabs produced according to the invention are used for building purposes or the like, or for skis or the like, the slabs consisting of laminated wood or block wood may be covered with a wooden coating for example plywood on the one vor the other side.

. gluedtogether will not then be solid, but shows transversely extending passages. Pierced boards or slabs may thus be sawn out of the block in the manner above described, which slabs will be of a light weight through the saving of material obtained. H

What I claim is:

1. The method of producing wooden planks resistant to warping which comprises assembling a plurality of glue coated elongated wooden strips into a stack with the strips extending in the same direction longitudinally of the stack, deforming the strips in the stack by applying pressure to bend the same along curved lines extending longitudinally from end to end of the stack, maintaining the stack pressure to retain the deformed condition until the glue has set to form a rigid block, leveling at least one longitudinal edge of the block thus formed sawing the block thus formed into slabs by longitudinal saw cutsextending substantially at right angles to the face of the glued joints between the strips, assembling two of such slabs in parallel co-planar relation with the levelled edges abutting and in such relation that the strips forming the same extend longitudinally thereof and the bends of the strips in one are oppositely disposed with respect to those in the other, and gluing the abutting edges of the so assembled slabs together to form a plank.

2. The. method of producing wooden planks resistant to warping which comprises assembling a plurality of glue coated elongated wooden strips into a stack with the strips extending in the same direction longitudinally of the stack, deforming the strips in the stack by applying pressure to bend the same along curved lines extending longitudinally from end to end of the stack, maintain-- ing the stack pressure to retain the deformed condition until the glue has set to form a rigid block, levelling the longitudinal edges of the blocks thus formed, assembling two of such blocks with levelled edges abutting and with the relation of the blocks such that the strips forming the same extend longitudinally thereof in the same direction and the bends of the individual strips in one block are oppositely disposed with respect to those in the other, gluing the so assembled blocks together and sawing the so assembled and glued blocks into planks by saw cuts extending longi tudinally substantially at right angles to the surface of the glued joints thereof.

3. The method of producing wooden planks resistant to warping which comprises assembling a plurality of elongated wooden strips into a stack with the strips extending in the same direction longitudinally of the stack and with glue applied to the contacting faces thereof, assembling with said stack a wooden mold block having a glued surface. curved in, thelongitudinal direction of said stack and facing the outermost strip at one longitudinal edge of the stack, deforming said stack by application of pressure thereon against said mold block to bend the strips to the contour of the curved surface thereof, maintaining the stack and mold block under pressure until the glue has set to form a rigid block including said mold block as a part thereof, levelling at leastone of the longitudinal edges of the block, sawing the block thus formed into parts by longitudinal saw cuts extending substantially at right angles to the face of the glued joints between the strips, assembling two of such parts in the same plane with levelled longitudinal edges thereof abutting each other and in such relation that the bends of the strips in one are at least partly opposed to those in the other and gluing the so assembled parts together to form a plank.

AXEL EUGEN LUNDBERG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 379,685 Cooley Mar. 20, 1888 1,078,776 Dunton Nov. 18, 1913 1,183,861 Everett May 23, 1916 1,299,705 Grosvenor Apr. 8, 1919 1,324,954 Carpenter Dec. 16, 1919 1,871,447 Elmendorf Aug. 16, 1932 2,155,375 Jablonsky Apr. 18, 1939 2,245,169 Von Ende et a1 June 10, 1941 2,245,170 Von Ende et a1 June 10, 1941 2,409,785 Newmark et a1 Oct. 22, 1946 FOREIGN PATENTS Number Country Date 544,137 Great Britain Mar. 30, 1942 

